Krack Attack: What You Need to Know

For the last decade, philosophers have been in agreement that there is another, deeper level within Maslow’s Hierarchy of Human Needs: WiFi Access.

We’re now at the point where even the most mundane devices in your house are likely to be WiFi enabled.

Today we learned that every single one of those devices–every single smartphone, wireless access point, and WiFi-enabled laptop–is vulnerable due to a fundamental flaw with WPA2(Wireless Protected Access v2).

It turns out that the WPA2 (Wireless Protected Access v2) protocol can be manipulated into reusing encryption keys in what’s being called the Krack Attack

Who Is Affected?

Because of how it works, this attack threatens all WiFi networks – and WiFi-enabled devices.

While the flaw is in the WPA2 protocol itself, how that protocol is implemented differs across device and software vendors. Apple’s iOS devices and Windows machines are mostly (as of now) unaffected since they don’t strictly implement the WPA2 protocol and key reinstallation.

The largest group affected are Android users and those other client devices that implemented the WPA2 protocol very strictly.

How the Attack Works

The attack works against WiFi clients and depends upon being within WiFi range of the target device. Attackers can use a special WiFi card that retransmits a previously used session key which forces a reinstallation of that key on the client device.

By doing so (and depending on exactly how WPA2 is implemented on the client device), the attacker can then send forged data to the client. For example, an attacker could silently manipulate the text and links on a web page.

How Practical Is the Attack?

An interesting twist to this attack is that it depends much more upon physical proximity in order to compromise a client since you need to be in WiFi range. An attacker also needs a somewhat specialized networking device and to be able to code up the exploit manually – since no software has yet been released for this attack.

What You Can Do To Protect Yourself Today

The more encryption you run at different layers of the communications stack the better. If you’re in charge of a website, this is just one more in a vast list of reasons you should be forcing SSL/TLS on your site.

VPNs are also a strong (additional) option: they’re inexpensive, easily configured, and can make Krack much less of an issue. An attacker can view/capture the encrypted data but won’t be able to do anything with it.

What You Can Do In The Coming Weeks

Update your devices – and be mindful of where and on what devices you’re using WiFi.

Every vendor is likely going to release a patch addressing this vulnerability: install the next product update that gets pushed to you – and encourage those around you to install security updates.

Neglected security updates are actually a large and persistent vulnerability: they’re there for a reason – install them! Greater adoption helps everyone. If you need more convincing, check out Lesson 4 of Troy Hunt’s Internet Security Basics.

What You Can Do Long Term

This may spark more (and long-needed) research into the areas of WiFi vulnerabilities.

While you can’t entirely prepare for the unknown, you can set yourself up to respond quickly by establishing good procedures for emergency patch management, implementing defense in depth by layering multiple different security systems and keeping all of your systems as up to date as possible.

This attack highlights that it’s important not to rely solely on any single layer of defense. For many home networks, this is, unfortunately, their only security layer. Always consider what happens when a layer of defense fails.

Michael Buckbee

Michael has worked as a syadmin and software developer for Silicon Valley startups to the US Navy and everything in between.